Denso Air Conditioner Error Code E4

E4 indicates that the fan motor's current draw has exceeded the threshold of the overcurrent relay, causing the protective device to activate and shut the unit down. This is a safety response to prevent motor or electrical damage from sustained high current. The unit will remain off until the fault is diagnosed and the code is manually reset.

No. The E4 code indicates the unit has already shut itself down as a protective measure. Attempting to bypass or repeatedly reset the fault without addressing the root cause risks motor burnout, damage to other electrical components, and in serious cases, a fire hazard. The system should remain off until the cause of the abnormal current draw is identified and corrected.

Repair costs depend on which component is at fault. A run capacitor replacement is typically the least expensive fix, often ranging from $75 to $200 including labor. Fan motor replacement is more involved and can range from $200 to $600 or more depending on the motor cost and labor rates in your area. Having a technician perform a current draw test and inspect the fan assembly first can help narrow down costs before committing to parts.

Some causes, such as a blocked or obstructed fan blade, can be safely inspected and cleared by a knowledgeable homeowner. However, diagnosing electrical faults like shorted motor windings, a failed capacitor, or a miswired overcurrent relay requires electrical testing equipment and familiarity with AC circuits. If you are not comfortable working with electrical components, it is best to contact a qualified HVAC technician.

Resetting the code by holding the SET TEMP UP and DOWN buttons simultaneously for 3 seconds will clear the fault and allow the unit to restart, but it does not fix the underlying issue. If the root cause of the high current draw is still present, the overcurrent relay will trip again and E4 will return. The reset should only be performed after the problem has been diagnosed and repaired.